[media] lnbh25: Fix lnbh25_attach() function return type

If CONFIG_DVB_LNBH25 is disabled, a stub static inline function is
defined that just prints a warning about the driver being disabled
but the function return type was wrong which caused a build error.

Fixes: e025273b86fb ("[media] lnbh25: LNBH25 SEC controller driver")

Reported-by: Fengguang Wu <[e-mail]>
Signed-off-by: Javier Martinez Canillas <[e-mail]>

drivers/media/dvb-frontends/lnbh25.h

···
 	struct lnbh25_config *cfg,
 	struct i2c_adapter *i2c);
 #else
-static inline dvb_frontend *lnbh25_attach(
+static inline struct dvb_frontend *lnbh25_attach(
 	struct dvb_frontend *fe,
 	struct lnbh25_config *cfg,
 	struct i2c_adapter *i2c)